One of the world’s biggest manufacturers of chemical and oil products has threatened the National Trust with legal action to force it to allow exploration for shale gas on its land.

Ineos Shale, part of the Ineos Group, which is headed by the billionaire Jim Ratcliffe, is the country’s leading shale gas company. It has government licences that give it access to about 1m acres of potential shale gas reserves.

These includes National Trust land at Clumber Park, near Worksop in Nottinghamshire.

However, the trust has refused access to the historic country park for seismic surveys, arguing that it has “a presumption against fracking on our land” and will not allow access for exploration.

An investigation by Greenpeace into fracking has established that Ineos Shale